This invention relates to an apparatus and method for building board or plank roads in undeveloped area over unprepared road beds for use by heavy trucks and machinery. It is customary in the oilfield industry to have the requirement of transporting heavy machinery on trucks to remote areas in fields and the like where there is no prepared roadbed. The axle loading of a typical heavy equipment truck is such that it is not feasible to drive it across a scraped or unprepared ground surface without experiencing sinking, jamming of the truck, and similar impediments.
It has therefore become customary to provide temporary roads to a wellsite in the oilfield industry by means of a plank road. The typical method for laying the plank road is as follows:
First, a path is made from an existing prepared road to the desired wellsite by means of a bulldozer. This path primarily consists of breaking down and pushing aside undergrowth and similar impediments. There is no preparation of an underbed or support surface drainage. Ditches may or may not be dug, depending upon the water level and the water table at the site concerned.
An impervious, waterproof layer is laid on the roadway. As will be shown, this layer must prevent sinking of the board road components, it is therefore usually a heavy plastic sheet such as Visquene.TM., vinyl, polyethelyne, or the like. The remainder of the road is constructed on the flotation layer.
The board road is constructed by laying a first layer lengthwise to the direction of travel. This first layer uses boards commonly referred to as 3.times.8's, although there is no such formal size of wood. Hardwood is provided for strength and durability; the cost of prepared hardwood lumber results in the use of the cheapest, roughest cut hardwood lumber available commercially. The length average fourteen feet but neither the length nor the size of this lumber is repeatable. The boards are usually warped. They are selected for cheapness of price because they are used for approximately two years and then discarded. The first layer is simply laid loose upon the ground.
A second layer is laid crosswise to this first layer. It is assembled closely spaced together, utilizes the same basic size of lumber and is tacked to the lower layer using six inch spikes or sixty penny nails.
The actual truck traffic is supported on a third board run layer. This board run layer comprises two longitudinal strips of boards each four feet wide. There is a four foot gap between the two strips. This produces in total the twelve foot industrially standard plank road. This layer is densely tacked using four nails approximately three feet apart per board.
The above description is general; individual contractors will vary but the overall technique remains the same.
The average board road is run for a distance of several hundred feet including a turnaround at the wellhead. In the turnaround, as in any turn area, the third layer of planks is laid as a continuous cover rather than as tracks.
Because of the cost of the lumber involved in the road, it is necessary to disassemble and salvage as much as possible after completion of the construction of the plank road and completion of the work at the wellhead. This removal involves ripping up the individual boards concerned, salvaging those that are not too badly damaged by this process and reusing them.
The typical plank road requires a team of fifteen men working for five to ten days to assemble; it requires a similar sized team for a similar period of time to salvage. The weight of the equipment and trucks that use the board road require the use of hardwoods in order to obtain a suitable support strength. The expense of the hardwoods is such that they must be salvaged. This expense is also the reason for using the cheapest grade available of the hardwoods concerned. Nonetheless, the average hardwood plank lasts less than two years in this service and then new planks must be obtained.